Quote from: Cap'n Redneck on Today at 04:32:39 AMCongrats on your new Rolling Block!

The crowned "C" on the right side of the receiver means it was manufactured at the "Carl Gustaf Stads Gevärsfaktori" (English: Rifle Factory of Carl Gustaf's Town) in Eskilstuna.

It does not look like the serial numbers on the receiver and barrel match, so probably a barrel swap at some time? 
You have the military rear sight, graduated in meters. 
Most sporterized Swedish Rolling Blocks had the rear sight swapped for a small fixed sight with one or two foldable leafs.

The two holes in the left side of the receiver puzzle me.... - maybe someone has tried to mount a hunting dioptre or scope on the gun at some time?

https://en.wikipedia.org/wiki/Remington_M1867

https://www.militaryrifles.com/swedish/m1867remington

Thanks for the detailed report! Yes, I am certain it was rebarreled at some point. The only thing that HAS to be done at this point is fitting the new extractor. That and acquire some brass that will work for the beastie!